31216005 Volvo.Penta Pressure pipe

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Fuel System Schematic (1) Fuel tank (2) Fuel return line (3) Priming pump (4) Fuel injection nozzle (5) Fuel injection line (6) Fuel injection pump (7) Primary fuel filter (8) Check valves (9) Fuel transfer pump (10) Secondary fuel filter (11) Constant purge valve (12) Fuel injection pump housingFuel transfer pump (9) pulls fuel from fuel tank (1) through both primary fuel filter (7) and check valves (8). From the fuel transfer pump, the fuel is pushed through secondary fuel filter (10) and to the fuel manifold in fuel injection pump housing (12). A bypass valve in the fuel transfer pump keeps the fuel pressure in the fuel system at 170 kPa (25 psi) to 280 kPa (41 psi).Constant purge valve (11) allows a constant fuel flow through fuel return line (2) and back to fuel tank (1). The constant bleed valve returns approximately 34 L (9 US gal) per hour of fuel and air to the fuel tank. This helps keep the fuel cool and free of air. Fuel injection pump (6) receives fuel from the fuel manifold. Fuel injection pump (6) pushes fuel at a very high pressure through fuel line (5) to fuel injection nozzle (4). The fuel injection nozzle contains very small holes in the tip. The small holes change the flow of fuel to a very fine spray. This fine spray improves the fuel combustion in the cylinder.Fuel Injection Pump
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Fuel Injection Pump (1) Check valve. (2) Inlet passage. (3) Fuel manifold. (4) Pump barrel. (5) Closed bypass port. (6) Pump plunger. (7) Slot. (8) Spring. (9) Scroll. (10) Spill port. (11) Lifter. (12) Fuel rack. (13) Gear. (14) Cam.There is one fuel injection pump for each cylinder in the engine. A fuel injection pump functions in two ways:
A fuel injection pump increases the pressure of the fuel.
A fuel injection pump sends a precise amount of fuel to the fuel injection nozzle.The fuel injection pump is moved by cam (14) of the fuel pump camshaft. When the camshaft turns, the cam raises the following components to the top of the stroke:
Pump plunger (6)
Lifter (11) The pump plunger always makes a full stroke. As the camshaft turns farther, spring (8) returns the same components to the bottom of the stroke.When the pump plunger is at the bottom of the stroke, any fuel at transfer pump pressure flows into inlet passage (2). This fuel flows around pump barrel (4) and to bypass port (5) .Fuel fills the area above the pump plunger.After the pump plunger begins the upstroke, fuel pushes out of the bypass port. Fuel pushes out until the top pump plunger closes the port. As the pump plunger continues to move up, the pressure of the fuel increases. At approximately 690 kPa (100 psi), check valve (1) opens. This allows fuel to flow through the fuel injection line to the fuel injection nozzle.As the pump plunger continues to move up, scroll (9) uncovers spill port (10). The fuel above the pump plunger flows through slot (7) and along the edge of scroll (9). Then, the fuel flows out of spill port (10) and back to fuel manifold (3). This is the end of the injection stroke. The pump plunger can continue to travel upward, but more fuel will NOT flow to the fuel injection nozzle.When the pump plunger travels downward, this plunger uncovers closed bypass port (5). The fuel begins to fill the area above the pump plunger again, and the pump is ready to begin another stroke.The rotation of the fuel pump changes the amount of fuel that is sent from the fuel injection pump to the fuel injection nozzle. Gear (13) is attached to the pump plunger. This gear meshes with fuel rack (12). The governor moves the fuel rack according to the engine's need for fuel.The pump plunger uses scroll (9) in order to control the amount of fuel that is pushed between closed bypass port (5) and spill port (10). A longer distance from the top of the pump plunger to the point of scroll (9) that uncovers spill port (10) will cause more fuel to be injected.To stop the engine, the pump plunger is rotated so that slot (7) on the pump plunger is in line with spill port (10). The fuel will now flow out of the spill port, and the fuel will NOT flow to the fuel injection nozzle.Fuel Injection Nozzle
The fuel injection nozzle is installed through the cylinder head into the combustion chamber. The fuel injection pump sends fuel with high pressure to the fuel injection nozzle. Then, the fuel is made into a fine spray for good combustion.
Illustration 3 g00318823
Fuel Injection Nozzle (1) Carbon dam. (2) Seal. (3) Passage. (4) Edge filter. (5) Orifice. (6) Valve. (7) Diameter. (8) Spring.Seal (2) is positioned against the cylinder head. This prevents leakage of compression from the cylinder. Carbon dam (1) keeps carbon out of the bore in the cylinder head's nozzle. Fuel with high pressure from the fuel injection pump flows into the inlet passage. Fuel then flows through edge filter (4) and into passage (3). The fuel continues to the area below diameter (7) of valve (6). When the fuel pressure against diameter (7) becomes greater than the force of spring (8), valve (6) lifts up. Valves (6) lift up when the fuel pressure rises above the Valve Opening Pressure of the fuel injection nozzle. When valve (6) lifts up, the tip of the valve comes off the nozzle seat, and the fuel will flow through orifice (5) into the combustion chamber. The injection of fuel continues until the pressure of fuel against diameter (7) becomes less than the force of spring (8). With less pressure against diameter (7), spring (8) pushes valve (6) against the nozzle seat. This stops the flow of fuel to the combustion chamber. The fuel injection nozzle cannot be disassembled, and no adjustments can be performed.Fuel Transfer Pump
The fuel transfer pump is a piston pump